The present invention relates to decorative boards and, more particularly, to a method of producing thermoset decorative boards which are improved in their decorative design, especially their brightness.
In order to impart decorative designs, especially glitter or brightness to thermoset decorative boards such as melamine and DAP decorative boards, reliance has heretofore been placed upon printing glitter or luster ink comprising metallic powders, a pearlescent pigment, etc. on the surface of a decorative board base or laminating a metal foil directly on that surface. In order to improve brightness when printing is carried out with glitter ink, however, it is necessary that a large amount of a glitter pigment with an increased particle size be incorporated into the ink. A glitter pigment having a large particle size tends to precipitate out, because difficulty is encountered in dispersing it uniformly in the ink. Further, when printing is performed with ink in which the pigment is on the point of separating out, brightness variations are likely to occur. A problem with the application of a pigment having a large particle size to gravure printing is that doctor lines occur frequently due to the abrasion of a doctor blade. For this reason, the glitter ink becomes so poor in its printability that a well-printed face cannot be obtained. In addition, some limitations, imposed upon the amount to be added and the size of the glitter pigment, render it impossible to obtain any thermoset decorative sheet which excels in brightness.
The direct lamination of metal foils is best-suited for brightening the overall surface of a decorative board. However, it is unsuitable for providing a brightened presentation of a fine design or pattern because of some limitation resulting from the processability of metal foils, etc., and only produces a decorative board which is cold to the touch since its entire surface is metal-finished.
Thus, a method for producing thermoset decorative boards without recourse to either printing or direct laminating of metal foils is still in great demand.